Blood flow reversal valves and related systems and methods

ABSTRACT

This disclosure relates to methods of reversing blood flow using a blood flow reversal valve that includes a first member having a first passage and a second passage, and a second member having a first passage and a second passage. The first and second members are rotatably fixed relative to one another such that the first passage of the first member is aligned with the first passage of the second member and the second passage of the first member is aligned with the second passage of the second member. A flow directing element is disposed in the cavity and is moveable between a first position in which the first passage of the first member and the first passage of the second member are fluidly connected and a second position in which the first passage of the first member and the second passage of the second member are fluidly connected.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional application and claims the benefit of U.S.application Ser. No. 13/785,537 filed Mar. 3, 2013, which claims thebenefit of U.S. Application Ser. No. 61/705,411, filed on Sep. 25, 2012.Both of these priority applications are incorporated by referenceherein.

TECHNICAL FIELD

This invention relates to blood flow reversal valves and related systemsand methods.

BACKGROUND

Many modern medical procedures use tubing sets of varying complexity towithdraw fluid from a patient, or to administer fluid to a patient, orto do both. One example of such a procedure is hemodialysis. Inhemodialysis, the patient's blood is cleansed by drawing it out of thepatient through a blood access site, typically via a catheter, andpassing it through an artificial kidney (often called a “dialyzer”). Theartificial kidney includes a semi-permeable membrane which removesimpurities and toxins by a process of diffusion. The purified blood isthen returned to the patient. An extracorporeal circuit including a pumpand hemodialysis tubing set is typically used to transport the bloodbetween the blood access site and the artificial kidney.

Many of the tubing sets used in medical procedures involvingextracorporeal treatment of fluid, such as hemodialysis, are configuredso that fluid can flow through the system in a desired direction duringthe medical procedure. A pumping device can be used to control the fluidflow rate in the system. In hemodialysis, for example, a peristalticpump is typically used to draw blood from the patient and move the bloodthrough the tubing set during the treatment procedure. Duringhemodialysis, blood is initially drawn from the patient's blood access(e.g., a vein or an artery, but more typically an arteriovenous graft orfistula) and flows through a series of connected tubing segments to theartificial kidney for cleansing. After passing through the artificialkidney, the blood then flows through other tubing segments that returnthe blood to the patient. Thus, there is generally a continuous circuitof blood flowing from the patient, through the artificial kidney, andthen back to the patient during treatment.

During hemodialysis, blood is generally drawn from an upstream positionin the blood access and then returned to a downstream position in theblood access. However, it has been found to be advantageous, for limitedtime periods, to reverse the direction that blood is received from andreturned to the patient during hemodialysis. When the blood flow isreversed, blood is initially drawn from a downstream position in theblood access. The blood then flows through tubing segments to theartificial kidney for treatment before it is returned to the upstreamposition in the blood access. Typically this procedure is carried out bytrained clinical personnel, e.g., dialysis clinicians. When the bloodflow is reversed, any of various parameters, such as blood access flowrate, can be measured or derived from measurements. The data can provideuseful information about the patient's condition and the effectivenessof the treatment. For example, practitioners can use informationgathered during periods of reversed blood flow to evaluate the conditionof the blood access, to get advanced warning on other health problems,such as access restrictions, and to prescribe preventive measures, suchas blood access revision or replacements, which are generally neededafter a few years of continuous dialysis.

SUMMARY

In one aspect of the invention, a blood flow reversal valve includes afirst member having a first passage and a second passage and a secondmember having a first passage and a second passage. The first and secondmembers are rotatably fixed relative to one another such that the firstpassage of the first member is aligned with the first passage of thesecond member and the second passage of the first member is aligned withthe second passage of the second member. A flow directing element isdisposed in a cavity formed between the first and second members. Theflow directing element is moveable relative to the first and secondmembers between a first position in which the first passage of the firstmember and the first passage of the second member are fluidly connectedand the second passage of the first member and the second passage of thesecond member are fluidly connected, and a second position in which thefirst passage of the first member and the second passage of the secondmember are fluidly connected and the second passage of the first memberand the first passage of the second member are fluidly connected.

In another aspect of the invention, a blood treatment system includes ablood flow reversal valve including a first member having a firstpassage and a second passage and a second member having a first passageand a second passage. The first and second members are rotatably fixedrelative to one another such that the first passage of the first memberis aligned with the first passage of the second member and the secondpassage of the first member is aligned with the second passage of thesecond member. A flow directing element of the blood flow reversal valveis disposed in a cavity formed between the first and second members, theflow directing element being moveable relative to the first and secondmembers between a first position in which the first passage of the firstmember and the first passage of the second member are fluidly connectedand the second passage of the first member and the second passage of thesecond member are fluidly connected, and a second position in which thefirst passage of the first member and the second passage of the secondmember are fluidly connected and the second passage of the first memberand the first passage of the second member are fluidly connected. Thesystem further includes a blood treatment device including a valveretention element configured to secure the blood flow reversal valve tothe blood treatment device and an actuator configured to move the flowdirecting element of the blood flow reversal valve from the firstposition to the second position.

In an additional aspect of the invention, a method of reversing bloodflow uses a blood flow reversal valve that includes a first memberhaving a first passage and a second passage, a second memberrotationally fixed relative to the first member and having a firstpassage and a second passage, and a flow directing element disposed in acavity formed between the first and second members. The method includesmoving the flow directing element of the blood flow reversal valve froma first position in which the first passage of the first member and thefirst passage of the second member are fluidly connected and the secondpassage of the first member and the second passage of the second memberare fluidly connected to a second position in which the first passage ofthe first member and the second passage of the second member are fluidlyconnected and the second passage of the first member and the firstpassage of the second member are fluidly connected. The first and secondmembers of the blood flow reversal valve remain fixed with respect toone another while the flow directing element moves from the firstposition to the second position.

Implementations can include one or more of the following features.

In some implementations, the flow directing element is rotatable about alongitudinal axis of the blood flow reversal valve.

In certain implementations, the first passages are aligned along an axisthat is substantially parallel to the longitudinal axis, and the secondpassages are aligned along an axis that is substantially parallel to thelongitudinal axis.

In some implementations, the flow directing element defines a first flowpath and a second flow path.

In certain implementations, the first flow path fluidly connects thefirst passage of the first member to the first passage of the secondmember and the second flow path fluidly connects the second passage ofthe first member to the second passage of the second member when theflow directing element is in the first position.

In some implementations, the first flow path fluidly connects the secondpassage of the first member to the first passage of the second memberand the second flow path fluidly connects the first passage of the firstmember to the second passage of the second member when the flowdirecting element is in the second position.

In certain implementations, the flow directing element is substantiallycylindrical.

In some implementations, the first and second flow paths aresubstantially semi-helical.

In certain implementations, each of the first and second flow paths hasa kidney-shaped cross-sectional area.

In some implementations, the flow directing element includes a bodydefining a central lumen and a partition extending through the lumen toform the first and second flow paths.

In certain implementations, the partition extends along a curved pathbetween a first end of the body and a second end of the body.

In some implementations, the partition extends along a substantiallysemi-helical path between the first end of the body and the second endof the body.

In certain implementations, each of the first and second flow paths hasa substantially half-circular cross-sectional area.

In some implementations, the partition twists by about 5 degrees toabout 180 degrees from a first end of the body to a second end of thebody.

In certain implementations, the partition twists by about 90 degreesfrom the first end of the body to the second end of the body.

In some implementations, the blood flow reversal valve further includesa projection that extends radially from the flow directing element.

In certain implementations, the projection extends through a slot thatis defined by at least one of the first and second members.

In certain implementations, the first and second members cooperate todefine the slot.

In some implementations, the slot extends circumferentially about thefirst and second members.

In certain implementations, the projection extends radially a sufficientdistance to engage an actuator of a blood treatment machine when theblood flow reversal valve is connected to the blood treatment machine.

In some implementations, the valve retention element includes resilientfingers configured to releasably engage fluid line connectors of theblood flow reversal valve.

In certain implementations, the actuator defines an opening configuredto receive a projection that extends radially from the flow directingelement of the blood flow reversal valve.

In some implementations, the actuator is configured to rotate the flowdirecting element.

In certain implementations, the blood treatment system further includesa controller programmed to move the actuator.

In some implementations, the controller is programmed to move theactuator at a predetermined time during a blood treatment.

In certain implementations, moving the flow directing element from thefirst position to the second position includes rotating the flowdirecting element relative to first and second members.

In some implementations, the flow directing element is moved from thefirst position to the second position by an actuator of a bloodtreatment machine.

In certain implementations, the method further includes transmitting asignal from a controller of the blood treatment machine to the actuatorto move the flow directing element.

In some implementations, the method further includes moving the flowdirecting element from the second position back to the first position.

In certain implementations, the method further includes running a bloodpump to force blood through the blood flow reversal valve.

In some implementations, the method further includes stopping the bloodpump prior to rotating the flow directing element from the firstposition to the second position.

In certain implementations, the method further includes measuring one ormore parameters of blood flowing through the blood flow reversal valve.

Implementations can include one or more of the following advantages.

Blood flow reversal valves described herein can advantageously reversethe blood flow through fluid lines connected thereto without requiringrepositioning or twisting of the fluid lines relative to one another.Reduced repositioning or twisting of the fluid lines can result in lesskinking or binding of the fluid lines and, as a result, better flowthrough the fluid lines.

Certain blood flow reversal valves described herein can be connected toa blood treatment machine (e.g., a hemodialysis machine) forautomatically reversing blood flow. As a result, blood flow reversal canbe achieved more easily with automated blood flow reversal valvesdescribed herein than with certain manually operated blood flow reversalvalves. Additionally, the system (e.g., a control unit or processor ofthe system) can be programmed to automatically reverse blood flow andtake measurements at designated times throughout the treatment. As aresult, such measurements can be taken at the ideal times throughout thetreatment even if a clinician is not present to manually reverse theblood flow.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other aspects, features, andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a blood flow reversal valve.

FIG. 2 is an exploded, perspective view of the blood flow reversal valveof FIG. 1.

FIGS. 3 and 4 are cutaway, perspective views of the blood flow reversalvalve of FIG. 1 with a central flow directing element of the valve infirst and second positions, respectively, to direct flow in a normaldirection and in a reverse direction, respectively.

FIG. 5 is a schematic illustration of a hemodialysis system including anextracorporeal blood line set that includes the blood flow reversalvalve of FIG. 1 and that is connected to a hemodialysis machine.

FIG. 6 is a perspective view of a valve receptacle of the hemodialysismachine of FIG. 5 without the blood flow reversal valve installed.

FIG. 7 is a schematic side view of the blood flow reversal valve of FIG.1 mounted in the valve receptacle of the hemodialysis machine of FIG. 6.

FIGS. 8A and 8B are schematic illustrations of blood flow through theblood flow reversal valve of FIG. 1 in its normal and reversedorientations, respectively.

FIG. 9 is an exploded, perspective view of a blood flow reversal valvethat includes a central flow directing element having kidney-shaped flowpassages that helically curve through the flow directing element.

FIGS. 10 and 11 are cutaway, perspective views of the blood flowreversal valve of FIG. 9 with the central flow directing element infirst and second positions, respectively, to direct blood flow in anormal direction and in a reverse direction, respectively.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a blood flow reversal valve 100 includes agenerally cylindrical first valve body 102, a generally cylindricalsecond valve body 104, and a central rotatable flow directing element120 disposed in a cavity 105 (shown in FIGS. 3 and 4) formed between thefirst and second valve bodies 102, 104. As shown in FIG. 2, the firstvalve body 102 and the second valve body 104 are formed of generallydisk-shaped end plates 142, 144 and circumferentially formed cylindricalwalls 146, 148 that extend from the end plates 142, 144. The first andsecond valve bodies 102, 104 are axially and rotationally fixed relativeto one another, and the flow directing element 120 is rotatable withinthe cavity 105.

The first and second valve bodies 102, 104 are secured to one another bymating features in the form of tabs 109 and slots 111 that are formedaround respective adjoining edges of the first and second valve bodies102, 104 and are spaced to align with one another for assembly of theblood flow reversal valve 100. The tabs 109 and slots 111 are configuredto be pressed into and coupled to one another. For example, the tabs 109and slots 111 can include snap-in style detents, resilient fingers thatdeflect and lock in place to connect the first and second valve bodies102, 104, or other interlocking features and elements to secure thevalve bodies 102, 104 together.

Still referring to FIGS. 1 and 2, the first valve body 102 includesblood line connectors 156, 158 that extend outwardly from the end plate142, and the second valve body 104 includes blood line connectors 160,162 that extend outwardly from the end plate 144. Fluid passages 106,108, 110, 112 extend through the blood line connectors 156, 158, 160,162 and the end plates 142, 144 to provide fluid communication with thecentral cavity 105 of the valve 100. Because the first and second valvebodies 102, 104 are rotationally fixed relative to one another, theblood line connectors 156 and 160 are fixed in axial alignment with oneanother, and the blood line connectors 158 and 162 are fixed in axialalignment with one another. As a result, the fluid passages 106 and 110are axially aligned with one another, and the fluid passages 108, 112are axially aligned with one another. However, as will be describedbelow, the flow directing element 120 can be rotationally positioned toeither fluidly connect the axially aligned fluid passage pairs (106/110and 108/112) of the first and second valve bodies 102, 104 or to fluidlyconnect the axially misaligned fluid passage pairs (106/112 and 108/110)of the first and second valve bodies 102, 104.

As shown in FIG. 2, the first valve body 102 includes a first slotportion 119A and the second valve body 104 includes a second slotportion 119B. The first and second slot portions 119A, 119B axiallyalign with one another when the first and second valve bodies 102, 104are secured to one another, as shown in FIG. 1, to form a slot 119. Apin 117 is secured to the flow directing element 120 and extendsradially outward through the slot 119. The pin 117 can be moved alongthe slot 119 in order to rotate the flow directing element 120 from afirst position that causes blood to flow through the valve 100 in anormal direction to a second position that causes blood to flow throughthe valve 100 in a reverse direction.

As shown in FIG. 2, the first valve body 102 includes visual indicators123, 125 that are used to indicate the orientation of the flow directingelement 120 relative to the first and second valve bodies 102, 104.Specifically, the visual indicators 123, 125 include the words “Normal”and “Reverse,” respectively, applied (e.g., printed, engraved, molded,applied using stickers, or applied by other suitable methods) toportions of the cylindrical wall 146 that are adjacent opposite endregions of the slot 119. As a result, the user can easily determine thatthe flow directing element 120 is in the normal flow position when thepin 117 is adjacent the indicator 123 and can easily determine that theflow directing element 120 is in the reverse flow position when the pin117 is adjacent the indicator 125.

Blood lines (e.g., tubing from a blood line set) can be connected to theblood line connectors 156, 158, 160, 162. For example, the blood linescan be slid over the blood line connectors 156, 158, 160, 162 andsecured (e.g., adhesively attached) to the blood line connectors 156,158, 160, 162. In some implementations, the blood lines are attached totheir associated blood line connectors by applying a solvent, such ascyclohexanone, to the blood line connectors and then sliding the bloodlines over the blood line connectors.

Referring to FIG. 2, the central rotatable flow directing element 120 isarranged and configured to rotate about a longitudinal axis 115 of theflow reversal valve 100 to direct flow in a desired manner between thefluid passages 106, 108 of the first valve body 102 and the fluidpassages 110, 112 of the second valve body 104. The rotatable flowdirecting element 120 is formed of a cylindrical outer wall 122 formingan inner flow cavity, and an inner, semi-helical partition 124 thatdivides the inner flow cavity into a first flow path 126A and a secondflow path 126B. The partition 124 is twisted about the longitudinal axis115 to form the semi-helical profile. As a result of this configuration,the first flow path 126A and the second flow path 126B follow twisted,curved profiles. The partition 124 typically has a smooth, gradualsurface that twists along the semi-helical profile. The first flow path126A and the second flow path 126B are substantially the same shape andsize, and follow similarly orientated paths through the flow directingelement 120.

Along its axial length, the partition 124 rotates or twists at an anglethat allows the axially aligned fluid passages 106 and 110 and theaxially aligned fluid passages 108 and 112 to be fluidly connected whenthe flow directing element is in the normal flow orientation (shown inFIG. 3) and that allows the axially misaligned fluid passages 106 and112 and the axially misaligned fluid passages 108 and 110 to be fluidlyconnected when the flow directing element is in the reverse floworientation (shown in FIG. 4). Specifically, when the flow directingelement 120 is in the normal flow orientation, the flow path 126Aconnects the fluid passage 106 to the fluid passage 110 and the flowpath 126B connects the fluid passage 108 to the fluid passage 112. Whenthe flow directing element 120 is in the reverse flow orientation, theflow path 126B connects the fluid passage 106 to the fluid passage 112and the flow path 126A connects the fluid passage 108 to the fluidpassage 110. Since the first and second flow paths 126A, 126B aresemi-circular and extend circumferentially almost 180 degrees within thecylindrical outer wall 122 of the flow directing element 120, the twistangle of the partition 124 typically only needs to be large enough toovercome the width of the fluid passages, as well as the width of thepartition 124. For example, the partition twist angle can be about 5degrees to about 180 degrees (e.g., about 60 degrees to about 120degrees, about 90 degrees).

The distance that the flow directing element 120 needs to be rotated inorder to reverse blood flow through the valve is dependent on the twistangle of the partition 124 and the arrangement of the fluid passages. Asthe twist angle increases, the rotational travel distance required toreverse blood flow through the valve 100 will also increase. Typically,the partition 124 is configured so that rotating the flow directingelement 120 by about 5 degrees to about 180 degrees (e.g., about 60degrees to about 120 degrees, about 90 degrees) about the longitudinalaxis 115 is sufficient to reverse the blood flow.

The flow directing element 120 is sized to create a press-fit type sealwithin the cavity 105 between the first and second valve bodies 102, 104when the first and second valve bodies 102, 104 are secured to oneanother. For example, the flow directing element 120 can have an axiallength that is greater than or equal to the axial length of the cavity105. In addition, the cylindrical wall 122 of the flow directing element120 can have an outer diameter that is greater than or equal to thediameter of the cavity 105.

The press-fit seal can help limit inadvertent flow out of the first flowpath 126A and the second flow path 126B. For example, a tight fitbetween the flow directing element 120 and end plates 142, 144 of thefirst and second valve bodies 102, 104 can help limit blood from flowingbetween the first and second flow paths 126A, 126B and/or help limitblood from flowing from the first and second flow paths 126A, 126B toouter regions of the cavity 105. Similarly, the tight fit between thecylindrical wall 122 of the flow directing element 120 and the innersurfaces of the walls 146, 148 of the first and second valve bodies 102,104 can help to prevent blood from leaking into the circumferentialspace around the flow directing element 120 in the event that bloodescapes one of the flow paths 126A, 126B.

The pin 117, which extends radially outward from the cylindrical outerwall 122 of the flow directing element 120, is typically integrallymolded with the cylindrical outer wall 122. Alternatively, the pin 117can be attached to the cylindrical outer wall 122 using other suitabletechniques. For example, the pin-like member 117 can be attached to thecylindrical outer wall 122 using fasteners (e.g., threaded fasteners),adhesive bonds, thermal bonds, or chemical bonds.

The first and second valve bodies 102, 104 and the flow directingelement 120 are typically made of one or more biocompatible high-impactthermoplastic or thermoset materials. In some implementations, the valvebodies 102, 104 are formed of acrylic-based multipolymer compound (e.g.,a biocompatible high impact MMA/styrene/acrylonitrile terpolymer orsimilar injection moldable thermoplastic compound). However, othermedical grade materials, such as polycarbonate, polysulfone, or blendsof these types of materials, can alternatively or additionally be used.The first and second valve bodies 102, 104 and the flow directingelement 120 are typically formed using injection molding techniques.However, other techniques, such as etching and machining, canalternatively or additionally be used.

FIGS. 3 and 4 are cutaway perspective views illustrating the flowdirecting element 120 in a normal flow orientation and a reverse floworientation, respectively. Portions of the cylindrical outer wall 122 ofthe flow directing element have been cutaway to provide a clear view ofthe twisted partition 124. As shown, the flow directing element 120 canbe rotated within the cavity 105 to fluidly connect the differentpassages with one another to reverse fluid flow within the blood flowreversal valve 100. In particular, when the flow directing element 120is in the normal flow orientation, as shown in FIG. 3, the partition 124is positioned relative to the stationary fluid passages such that theaxially aligned fluid passages 106, 110 are fluidly connected via theflow path 126A and the axially aligned fluid passages 108, 112 arefluidly connected via the flow path 126B. When the flow directingelement 120 is in the reverse flow orientation, as shown in FIG. 4, thepartition 124 is positioned relative to the stationary fluid passagessuch that the axially misaligned fluid passages 106, 112 are fluidlyconnected via the flow path 126B and the axially misaligned fluidpassages 108, 110 are fluidly connected via the flow path 126A.

FIG. 5 schematically illustrates a hemodialysis system 200 including ablood line set that includes the blood flow reversal valve 100 connectedto a hemodialysis machine 201. The blood flow reversal valve 100 isfitted to a valve receptacle 250 mounted along a front face of thehemodialysis machine 201. Arterial and venous blood lines 212 and 214are connected to blood line connectors 158 and 156, respectively, of thefirst valve body 102, and outlet and inlet blood lines 206 and 208 aresecured to blood line connectors 162 and 160, respectively, of thesecond valve body 104.

As shown in FIG. 5, the second valve body 104 is fluidly connected to apump 202 via the outlet blood line 206 and is fluidly connected to adialyzer 204 via the inlet blood line 208. The pump 202 is fluidlyconnected to the dialyzer 204 via a connection tube 210. On the oppositeside of the valve 100, the arterial and venous blood lines 212, 214 arefluidly connected to the first valve body 102 and can be connected to apatient during treatment. During treatment, as will be discussed below,the flow directing element 120 of the valve 100 can be rotated toreverse blood flow within the arterial and venous blood lines 212, 214without reversing operation of the blood pump 202 or twisting the lines206, 208, 212, 214.

The blood lines 206, 208, 210, 212, and 214 can be any of various typesof blood lines. In some embodiments, the blood lines are formed of oneor more compliant materials, such as polyvinylchloride (PVC),Di(2-ethylhexyl) phthalate (DEHP), polyolifins, etc. However, otherconventional blood line materials can alternatively or additionally beused.

The pump 202 can be any of various pumping devices capable of forcingblood through system 200. Examples of suitable pumping devices includeperistaltic pumps, such as those available from Sarns, Inc. (Ann Arbor,Mich.).

The dialyzer 204 can include any of various dialyzers. Examples ofsuitable dialyzers include Fresenius Optiflux® series dialyzers.

Referring to FIG. 6, the valve receptacle 250 includes valve retentionelements (e.g., resilient fingers or clamping devices) 252 that aresized and configured grasp the blood flow reversal valve 100 during use.The valve retention elements 252 each have finger-like elements 253 thatprotrude inward towards a valve insertion area. The finger-like elements253 are configured to grasp the blood line connectors 156, 158, 160, 162and to help to keep the blood flow reversal valve 100 generallystationary during blood treatment and flow reversal.

A pin movement device or actuator 254 is located substantially in thecenter of the valve retention elements 252 and protrudes through a hole256 formed in the face of the blood treatment machine. The actuator 254has a pin slot 258 that is sized and configured to receive the pin 117of the blood flow reversal valve 100. As shown, the actuator 254 is inthe form of a rotating member 260 that, when rotated, can move the pin117 relative to the stationary blood flow reversal valve 100. Therotating member 260 is connected to a motor (e.g., an electric motor)that can rotate the rotating member 260. As a result, the actuator 254can move the flow directing element 120 and reverse the blood flowthrough the valve 100.

The hemodialysis machine 201 includes a controller (e.g., amicroprocessor) that is electrically connected to the motor connected tothe rotating member 260. Signals can be sent from the controller to themotor to operate the rotating member 260. The controller is alsotypically connected to a timer and/or sensors of the hemodialysismachine 201 so that the controller can receive signals from thosecomponents and operate the rotating member 260 based on the signalsreceived from those components. In some implementations, the controlleris programmed to transmit signals to rotate the rotating member 260 andthus reverse blood flow through the valve 100 at designated times duringtreatment. In such implementations, the controller can receive signalsfrom the timer indicating how long the treatment has been underway andcan cause the rotating member 260 to rotate when a predetermined time isreached. Alternatively or additionally, the controller can be programmedto rotate the rotating member 260 upon receiving signals indicating thatreadings of a sensor (e.g., a pressure sensor) are outside of apredetermined range.

FIG. 7 illustrates a schematic side view of the blood flow reversalvalve 100 mounted in the valve receptacle 250. As shown, the blood lineconnectors 156, 158, 160, 162 are clipped into their associated valveretention elements 252 so that the blood flow reversal valve 100 is heldgenerally stationary relative to the hemodialysis machine 201 duringuse. The pin 117 of the valve 100 is disposed in the pin slot 258 of therotating member 260 so that the blood flow reversal valve 100 is engagedby the valve receptacle 250 for use.

FIGS. 8A and 8B illustrate an exemplary method of using the hemodialysissystem 200 to perform hemodialysis. Referring to FIG. 8A, the arterialand venous blood lines 212 and 214 are connected to an artery and vein,respectively, of a patient. Any of various known methods can be used toconnect the arterial and venous blood lines 212 and 214 to the patient.For example, the blood lines 212 and 214 can be fluidly connected to afistula, graft or shunt implanted within a patient, which connects avein of the patient to an artery of the patient.

To begin treatment, the valve 100 is configured in the normal floworientation in which the arterial blood line 212 is fluidly connectedwith the outlet blood line 206 via the second flow path 126B of the flowdirecting element 120 and the venous blood line 214 is fluidly connectedwith the inlet blood line 208 via the first flow path 126A of the flowdirecting element 120. When in this position, as discussed above, thepin 117 is aligned with the indicator 123, which displays the term“Normal,” to inform the clinician that valve 100 is in the normal flowposition. The blood pump 202 is then activated, causing blood to bedrawn from the artery of the patient through the arterial blood line 212and the outlet blood line 206 to the pump 202. The blood is then forcedthrough the connection line 210 to the dialyzer 204, where the blood isfiltered. After exiting the dialyzer 204, the blood continues throughthe inlet blood line 208 and the venous line 214 to the patient. Theblood re-enters the vein of the patient via the venous line 214. Theblood is generally pumped through the system 100 at a flow rate ofapproximately 300 ml/min. However, other flow rates are possible. Thepump 202 can, for example, be configured to pump the blood at a rate ofabout 50 ml/min to about 600 ml/min.

As discussed above, it may be desirable at certain times duringhemodialysis to reverse the flow of blood. Certain parameters can, forexample, be measured in the standard flow and reversed flowconfigurations and compared to one another in order to determine theblood access flow rate. Examples of methods of determining blood accessflow rates are described, for example, in U.S. Pat. Nos. 5,830,365 and6,648,845, which are incorporated by reference herein.

When the dialysis system 200 determines that it is appropriate toreverse blood flow through the blood flow reversal valve 100, the pump202 is typically briefly stopped. Once the blood flow has stopped, thecontroller of the dialysis system 200 sends a signal to rotating member260 of the valve receptacle 250. The rotating member 260 is then rotatedto move the pin slot 258 (i.e., to move the pin slot 258 downward in theorientation shown in FIG. 7) to move the pin 117. As the pin 117 movesfrom the normal flow position towards the reverse flow position, thepartition 124 rotates within the blood flow reversal valve 100 toward aposition in which it fluidly connects the fluid passages in a manner toinduce a reserved flow.

After being placed in the reverse flow position illustrated in FIG. 8B,the arterial blood line 212 is fluidly connected with the inlet bloodline 208 via the second flow path 126B of the flow directing element120, and the venous blood line 214 is fluidly connected with the outletblood line 206 via the first flow path 126A of the flow directingelement 120. The pump 202 is then restarted, causing blood to be drawnfrom the vein of the patient and drawn through the venous blood line 214and the outlet blood line 206 to the pump 202. The blood is then passedthrough the dialyzer 204 and flows through the inlet blood line 208. Theblood then passes through the valve 100 to the arterial blood line 212.The blood re-enters the artery of the patient via the arterial bloodline 212. During reversed flow, the pump 202 is operated in the samemanner (i.e., the same direction) in which it is operated during normalflow. The pump 202 typically pumps blood at a rate of about 300 ml/minduring reversed flow operation. However, other flow rates are possible.The pump 202 can, for example, be configured to pump the blood at a rateof about 50 ml/min to about 600 ml/min during periods of reversed bloodflow.

After the desired period of reversed blood flow is completed, the pump202 is again stopped and the flow directing element 120 is rotated backinto the normal flow position. The pump 202 is then restarted, and theblood treatment is resumed.

While various embodiments have been described above, other embodimentsare possible.

While the flow directing element 120 has been described as beingpress-fitted within the cavity 105 formed between the first and secondvalve bodies 102, 104 in order to create liquid-tight seals between theends of the flow directing element 120 and the end plates 142, 144 ofthe first and second valve bodies 102, 104, other sealing techniques canalternatively or additionally be used. In some embodiments, for example,gaskets are attached to each axial end of the flow directing element120. The gaskets can have a shape that corresponds to the shapes of theend surfaces of the flow directing element 120. For example, each of thegaskets can include an outer ring-shaped member and a central partitionthat extends through a central aperture of the ring-shaped member toform two semi-circular flow passages. The gaskets can be attached (e.g.,adhesively attached, thermally bonded, chemically bonded, orover-molded) to the ends of the flow directing element 120 such that thefluid passages of the gaskets align with the flow paths 126A and 126B ofthe flow directing element 120. The gaskets are compressed between theends of the flow directing element 120 and the end plates 142, 144 ofthe first and second valve bodies 102, 104 to form a liquid-tight sealbetween the ends of the flow directing element 120 and the end plates142, 144 of the first and second valve bodies 102, 104. The gaskets caninclude one or more biocompatible materials that have a durometer ofabout 30 Shore D to about 40 Shore D (e.g., about 30 Shore D). Examplesof materials from which the gaskets can be formed include polyisoprenelatex, silicone, krayton, and blends of these types of materials.

In some implementations, the flow directing element (e.g., thecylindrical outer wall 122 and/or the partition 124) and/or the firstvalve body 102 and the second valve body 104 can include a fluid sealingelement (e.g., an O-ring style sealing wiper, or other sealing elements)disposed along its edges to limit fluid from inadvertently flowing fromthe first and second flow paths.

In some implementations, one of the valve bodies includes a recessedslot portion that substantially defines the entire slot and the oppositevalve body does not include a slot portion. Alternatively oradditionally, the flow directing element can include other types ofprojections that allow the flow directing element to be moved within theblood flow reversal valve. For example, in some implementations, theflow directing element includes a region having teeth exposed within theslot that matingly engage teeth of a gear that is external to the bloodflow reversal valve.

While the blood flow reversal valve state indicators 123, 125 have beendescribed as being in the form of words applied to the first valve body,other types of indicators can be used for indicating the state of theblood flow reversal drive. For example, in some implementations, coloredfigures or suggestive symbols can be applied to indicate the state ofthe blood flow reversal valve. The indicators can alternatively oradditionally be applied to other components of the blood flow reversalvalve. For example, the indicators can be applied to the second valvebody, or the indicators can be applied to portions of the flow directingelement that become visible within slot when the flow directing elementis rotated to the position associated with the particular indicator.

While the flow directing element 120 has generally been described ashaving a cylindrical cavity divided into two substantially half-circleshaped helical flow paths by the generally helical partition 124, otherconfigurations are possible. FIG. 9, for example, is an exploded,perspective view of an alternative blood flow reversal valve 300 havinga flow directing element 320 that includes two helical flow paths 322,324. Each of the flow paths 322, 324 has a substantially curvedcross-sectional shape (e.g., a kidney shaped cross-sectional area) thatfollows a substantially helical path through the flow directing element320. The flow directing element 320 is disposed in the cavity 105between the first and second valve bodies 102, 104 and is rotatablebetween a normal flow position and a reverse flow position to fluidlyconnect different fluid end plate passages 106, 108, 110, 112. The flowdirecting element 320 can be sealed within the cavity 105 using any ofthe various techniques described above with respect to the flowdirecting element 120.

The curved flow paths 322, 324 can improve fluid flow through the bloodflow reversal valve 300, as well as reduce blood coagulation. Thegeometry and arrangement of the curved flow paths 322, 324 can alsoaffect the angular distance that the flow directing element 320 needs tobe rotated in order to reverse the flow though the blood flow reversalvalve. The rotation angle by which the flow directing element 320 mustbe rotated to reverse the flow through the valve 300 depends on severalfactors including the axial length and twist angle of the flow paths322, 324. The required rotation angle can typically be determined bysubtracting the twist angle of the flow path from 180 degrees.Therefore, as the twist angle increases (and the span and size of theflow path 322 increases), the rotation angle needed to reverse the flowdecreases. The flow paths 322, 324 are typically designed such thatrotating the flow directing element 320 by about 5 degrees to about 180degrees (e.g., about 60 degrees to about 120 degrees, about 90 degrees)about the longitudinal axis of the valve 300 is sufficient to reverseflow through the valve 300.

FIGS. 10 and 11 are cutaway perspective views that illustrate thedifferent positions of the flow directing element 320 relative to thefirst and second valve bodies 102, 104. Referring to FIG. 10, when theflow directing element 320 is arranged in a first position (e.g., thenormal flow position) relative to the first and second valve bodies 102,104, the first flow path 322 fluidly connects the axially aligned fluidpassages 106 and 110 and the second flow path 324 fluidly connects theaxially aligned fluid passages 108 and 112. Referring to FIG. 11, whenthe flow directing element 320 is arranged in a second position (e.g.,the reversed flow position) relative to the first and second valvebodies 102, 104, the first flow path 322 fluidly connects the axiallymisaligned fluid passages 108 and 110 and the second flow path 324fluidly connects the axially misaligned fluid passages 106 and 112 toreverse the blood flow through the valve 300.

The valve 300 can be incorporated into a blood line set and connected tothe hemodialysis machine 201 in the manner described above with respectto the valve 100. Thus, the actuator 254 can be used to automaticallyreverse blood flow through the valve 100 during treatment.

While the blood flow reversal valves 100, 330 include mating tabs andslots that are used to secure the valve bodies 102, 104 to one another,other devices or techniques can be used. For example, alternatively orin addition to interlocking tabs and slots, fasteners (e.g., threadedfasteners (e.g., bolts or screws), rivets, or other fasteners) can beused. In some implementations, one of the valve bodies includes acircumferentially formed recess or lip that is sized to receive and beengaged by a circumferentially formed resilient conical ring disposedaround an adjoining edge or the other valve body. Using thecircumferentially formed recess and ring, the two valve bodies can bepressed together and the ring can snap into the recess to secure thevalve bodies together. In some implementations, the first and secondvalve bodies 102, 104 include threaded portions that permit them to bescrewed to one another. In some implementations, separate devices, suchas clamps can be used to press the first valve body 102 onto the secondvalve body 104.

While the actuator 254 of the hemodialysis machine 201 has beendescribed as being rotatable, the actuator can alternatively include avertically moveable element having a hole to receive the pin of theblood flow reversal valve. Alternatively or additionally, the valveretention element can include a moving gear configured to engage amating gear mounted on the blood flow reversal valve to move the flowdirecting element.

While the blood lines have been described as being bonded to the bloodline connectors using an adhesive, other techniques can be used. Forexample, the blood lines can be thermally bonded and/or chemicallybonded to the blood line connectors. As another example, the blood linesand blood line connectors can include mating luer locking mechanismsthat can be used to secure the blood lines to the blood line connectors.

While the blood flow reversal valve has been described as being used incombination with a dialysis machine that is able to automaticallyreverse the blood flow through the valve when desired, otherconfigurations are possible. For example, in some implementations, auser (e.g., a clinician, patient, or other person administering a bloodtreatment process) manually moves the flow directing element (e.g., bygrasping the projection extending radially from the flow directingelement) from the normal flow position to the reversed flow position.

While the blood flow reversal valve has been described as a componentfor a hemodialysis system, the blood flow reversal valve canalternatively or additionally be used with other types of bloodtreatment systems where flow reversal is desired. Examples of othertypes of blood treatment systems include plasmapheresis, autotransfusiondevices, and hemoabsorptive devices.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made without departing fromthe spirit and scope of the invention. Accordingly, other embodimentsare within the scope of the following claims.

What is claimed is:
 1. A method of reversing blood flow using a bloodflow reversal valve that comprises a first member having a first passageand a second passage, a second member rotationally fixed relative to thefirst member and having a first passage and a second passage, and a flowdirecting element disposed in a cavity formed between the first andsecond members, the flow directing element comprising a planar memberextending through a semi-helical path, the method comprising: moving theflow directing element of the blood flow reversal valve from a firstposition in which the first passage of the first member and the firstpassage of the second member are fluidly connected and the secondpassage of the first member and the second passage of the second memberare fluidly connected to a second position in which the first passage ofthe first member and the second passage of the second member are fluidlyconnected and the second passage of the first member and the firstpassage of the second member are fluidly connected, wherein the firstand second members of the blood flow reversal valve remain fixed withrespect to one another while the flow directing element moves from thefirst position to the second position.
 2. The method of claim 1, whereinmoving the flow directing element from the first position to the secondposition comprises rotating the flow directing element relative to firstand second members.
 3. The method of claim 1, wherein the flow directingelement is moved from the first position to the second position by anactuator of a blood treatment machine.
 4. The method of claim 3, furthercomprising transmitting a signal from a controller of the bloodtreatment machine to the actuator to move the flow directing element. 5.The method of claim 1, further comprising moving the flow directingelement from the second position back to the first position.
 6. Themethod of claim 1, further comprising running a blood pump to forceblood through the blood flow reversal valve.
 7. The method of claim 6,further comprising stopping the blood pump prior to rotating the flowdirecting element from the first position to the second position.
 8. Themethod of claim 1, further comprising measuring one or more parametersof blood flowing through the blood flow reversal valve.